Secure electronic voting devices are well-known in the art. An example is shown in U.S. Pat. No. 7,270,269 to Iyer et al. incorporated by reference herein. In Iyer, a conventional electronic voting system makes use of a write-once recording medium for capturing votes cast by voters. Voters interact with a voting system using a touch screen display or other electronic mechanism for casting votes. The system uses an array of physical electronic fuses to register the votes. Due to their characteristics (i.e., once the fuse is “blown”) these fuses cannot be tampered with by restoring them to an unaltered state.
Iyer explains that the benefits of his system include the fact that the fuses are used in removable cartridge form, and have two different modes: 1) a writing mode in which the votes are recorded; and 2) a reading mode during which the votes are identified. An encrypted ID can also be stamped in the cartridge to identify it uniquely. Other types of data could be recorded of course, including an association with a particular voting machine, a particular region, etc. The e-fuse cartridge and array (225) described by Iyer is shown generally in FIG. 2.
Fuse elements have their limitations, however, including the fact that some may require external laser or explosion method for programming. This will require that openings be made to the passivation in the areas of fuse elements. Even in the applications where the fuse elements are electrically programmed, there is a need for special circuitry and special pads that can handle high current in order to supply enough energy to program the fuse. This makes fuse programming implementation not very easily applied at field level. In addition, due to the programming requirement, there is the need to connect one terminal of every programmable fuse element to a power supply or other common node, thus limiting the flexibility in the design of the sensing circuit. One additional issue with the fuse elements is that they are inherently one-time-destructive programming element, making testing and screening at wafer production nearly impossible.